Enabling Claude Fable 5

Enabling Claude Fable 5

If you have enabled Claude Fable 5 through the Google Cloud Model Garden but it does not appear in the extension's model picker (or fails with a 403 PERMISSION_DENIED error during discovery), you may need to perform a one-time project-level configuration.

The Problem

Unlike other Claude models (like Sonnet or Haiku), Claude Fable 5 requires a mandatory provider data-sharing opt-in. If this is not enabled for your project, the Vertex AI API will reject requests to this model, and the extension's Smart Discovery process will be unable to register it.

Symptoms

• Claude Fable 5 enabled in model garden but is missing from the VS Code Chat model picker.
• The extension's output channel shows an error when probing for claude-fable-5.
• Other models in the same project work perfectly.

The Fix

To enable the model, you must explicitly opt-in to data sharing with Anthropic for your project. This is a one-time API call per project and location.

Using curl

Run the following command in your terminal (ensure you have gcloud authenticated):

# Set your Google Cloud Project ID
PROJECT_ID="your-project-id"
LOCATION = "your-location" # usually "global" 

curl -X POST \
  -H "Authorization: Bearer $(gcloud auth print-access-token)" \
  -H "Content-Type: application/json" \
  "https://aiplatform.googleapis.com/v1beta1/projects/${PROJECT_ID}/locations/${LOCATION}/publishers/anthropic/models/claude-fable-5:setPublisherModelConfig" \
  -d '{
    "publisherModelConfig": { "dataSharingEnabledProvider": "ANTHROPIC" },
    "updateMask": "dataSharingEnabledProvider"
  }'

Why this is required

Newer-generation models like Fable 5 are configured by Anthropic to require data sharing as a condition of use. This means prompts and completions are sent to Anthropic (subject to their retention and review policies). For these models, there is no "no-sharing" mode—you must opt in to use them on the platform.

Verification

After running the fix:

1. Run the command Google Agent Platform: Refresh Models in VS Code.
2. Check the Vertex AI Models Chat Provider output channel.
3. Claude Fable 5 should now appear in your model picker.

Requirements & Caveats

• IAM Permissions: You need the aiplatform.endpoints.setPublisherModelConfig permission. If you lack this, a Project Admin must run the command.
• Data Governance: Enabling this means your organization agrees to share Fable 5 data with Anthropic. Ensure this aligns with your company's compliance policies.
• Persistence: This setting persists; you do not need to repeat it unless you switch projects or locations.